A prior art antenna apparatus is equipped with a circularly polarized wave generator and a polarizer, which are mounted on a rotary joint or a rotary mechanism, so as to allow integral rotation of a reflector and a primary radiator (refer to the following non-patent reference 1).
[Non-Patent Reference 1]
Takashi Kitsuregawa, ‘Advanced Technology in Satellite Communication Antennas: Electrical & Mechanical Design’, ARTECH HOUSE INC., pp. 232 to 235, 1990.
A problem with the prior art antenna apparatus constructed as mentioned above is that while it can rotate both the reflector and the primary radiator in a direction of an elevation angle or in a direction of an azimuth angle, the part of the prior art antenna apparatus which is arranged above the rotary mechanism has a very large size and has a high position, and therefore the prior art antenna apparatus lacks in installation stability because the circularly polarized wave generator and the polarizer are placed on the rotary joint or the rotary mechanism.
The present invention is made in order to solve the above-mentioned problem, and it is therefore an object of the present invention to provide an antenna apparatus having a low profile and high installation stability without impairing its electric characteristics.